Service Repair

The Trainer #144: Determining Mechanical Functionality Through Electrical Current Flow

Jan. 17, 2024

Utilizing a multi-trace lab scope and current probe Technical Editor Brandon Steckler captures aspects of circuit operation in both a functional A/C compressor clutch circuit as well as a faulted one.

Brandon Steckler

In this episode of The Trainer, master diagnostician and Motor Age Technical Editor, Brandon Steckler discusses how to determine the functionality of a component via current flow. Utilizing a multi-trace lab scope and current probe Brandon captures aspects of circuit operation in both a functional A/C compressor clutch circuit as well as a faulted one. It all begins with studying the wiring diagram for the vehicle in question and building a game plan before approaching the vehicle. Executing the game plan at the vehicle yields answers to the questions.

The difference between a functional A/C compressor clutch and one that does not function is easily discerned by viewing the current ramp waveform. Brandon points out key signatures in the capture that tell the story of an issued command and an adequate response to the command being issued. These include:

Available voltage to the A/C compressor clutch relay
The output voltage from the relay once activated (command issued)
Current flow through the A/C compressor clutch field coil circuit (electrical work being performed)
Physical shuttling of the A/C compressor clutch (physical work being performed)

Allow your approach to help you gain insight into system functionality, regardless of the systems or components you are faced with. This technique being discussed applies to every vehicle you will encounter so, tune in and take your vehicle diagnostics to the next level.

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About the Author

Brandon Steckler | Technical Editor | Motor Age

Brandon began his career in Northampton County Community College in Bethlehem, Pennsylvania, where he was a student of GM’s Automotive Service Educational program. In 2001, he graduated top of his class and earned the GM Leadership award for his efforts. He later began working as a technician at a Saturn dealership in Reading, Pennsylvania, where he quickly attained Master Technician status. He later transitioned to working with Hondas, where he aggressively worked to attain another Master Technician status.

Always having a passion for a full understanding of system/component functionality, he rapidly earned a reputation for deciphering strange failures at an efficient pace and became known as an information specialist among the staff and peers at the dealership. In search of new challenges, he transitioned away from the dealership and to the independent world, where he specialized in diagnostics and driveability.

Today, he is an instructor with both Carquest Technical Institute and Worldpac Training Institute. Along with beta testing for Automotive Test Solutions, he develops curriculum/submits case studies for educational purposes. Through Steckler Automotive Technical Services, LLC., Brandon also provides telephone and live technical support, as well as private training, for technicians all across the world.

Brandon holds ASE certifications A1-A9 as well as C1 (Service Consultant). He is certified as an Advanced Level Specialist in L1 (Advanced Engine Performance), L2 (Advanced Diesel Engine Performance), L3 (Hybrid/EV Specialist), L4 (ADAS) and xEV-Level 2 (Technician electrical safety).

He contributes weekly to Facebook automotive chat groups, has authored several books and classes, and truly enjoys traveling across the globe to help other technicians attain a level of understanding that will serve them well throughout their careers.